Increasing concerns about continuous decline in non-renewable energy from petroleum resources, fluctuations in oil and its related fuels prices, greenhouse gas emissions as well as increasing energy demand in the world, investigation on other sources of energy is of great importance. Among these sources, bio-fuels such as biodiesel, biogas and ethanol are important ones. In terms of optimum usage of energy and its structural modification, which is an important index of sustainable development in each country, being independent to a particular type of energy, i.e. using different types of energy in the consumption fuel basket is essential. Currently, diesel engines are as an essential part of providing driving force for the road and off the road vehicles. However, these engines are one of the major consumers of fossil fuel and are considered as one of the most important factors of noise and environmental pollutions. Due to the exhaust gas quality (low pollution), the stability and biodegradable potential, biodiesel is considered as a perfect alternative for diesel fuel in the world. Eruca Sativa from Brassica family is a native Iranian oil seed which can grow in poor areas and has been known for centuries in Iran. Extracted oil from the seeds of this plant is capable of producing biodiesel. This study was aimed to study on a Ford diesel engine performance that uses the various volumetric ratio of the biodiesel produced from Eruca Sativa oil seeds to the conventional gasoline #2 (B 0 , B 5 , B 10 , B 15 , B 20 , B 25 , B 35 , B 50 , B 75 , B 100 ). In this regard, the studied parameters were power, torque and fuel consumption under full load condition at rotational speed range of 1500 to 4800 rpm with increment of 500 rpm. Also, the emission values of pollutants at the speeds of 2500, 3500 and 4500 rpm was investigated. Moreover, the engine heat balance and distributing manner of the released thermal energy from different fuel blends at both speeds of 2500 and 4000 rpm under part loads of 25%, 50%, and 75% and full load (100%) were studied. Results showed that by adding up to 15% of volumetric ratio of the biodiesel to the gasoline, the engine torque and power slightly improved and the maximum increase in the torque (1.69 %) occurred for B 15 . But for mixtures with more than 15% volumetric ratio, the engine torque decreased and the maximum reduction occurred for B 35 . Application of B 5 , B 10 and B 15 reduced the brake specific fuel consumption, and B 5 with a reduction of 11.75% in fuel consumption showed the most desirable condition. Other fuel blends increased the brake specific fuel consumption and B 35 with 41.71% showed the highest increase. Except for full load (100%) at both rotational speeds of 2500 and 4000 rpm, the exhaust gas temperature decreased as the percentage of biodiesel in the fuel mixture increased. At all speeds, emission of pollutants including CO, CO 2 and NO x in the fuels containing biodiesel were less than the corresponding values for pure gasoline. The amount of unburned hydrocarbons (UHC) increased as the percentage of biodiesel in the mixture increased. Engine heat balance revealed that under part load of 50%, the share of engine brake power from total fuel thermal power for different blends were averagely about 28% and 25% at speeds of 2500 and 4000 rpm, respectively. Exhaust losses was about 16% on average for both speeds and cooling system losses were averagely about 48% and 38% at speeds of 2500 and 4000 rpm, respectively. Under part load of 75%, for various mixtures on average, the engine brake power portion from fuel heat power were about 30% and 28%, and cooling system losses portion were 41% and 33% at speeds of 2500 and 4000 rpm, respectively. In this case, the exhaust losses were about 18% and 17% at speeds of 2500 and 4000 rpm, respectively. In general, by increasing the percentage of biodiesel in the fuel mixture, the share of cooling system heat losses and exhaust heat losses both increased. KeyWord : Biodiesel, Diesel Engine Performance, Eruca Sativa , Heat Balance, Pollutants Emission